Department of Cell Biology, University of Medicine and Dentistry of New Jersey, 2 Medical Center Drive, Stratford, NJ 08084, USA.
Mol Cell Biol. 2010 Jun;30(12):2947-56. doi: 10.1128/MCB.00226-10. Epub 2010 Apr 19.
Biogenesis of eukaryotic ribosomes requires a number of RNA helicases that drive molecular rearrangements at various points of the assembly pathway. While many ribosome synthesis factors are conserved among all eukaryotes, certain features of ribosome maturation, such as U8 snoRNA-assisted processing of the 5.8S and 28S rRNA precursors, are observed only in metazoan cells. Here, we identify the mammalian DEAD box helicase family member Ddx51 as a novel ribosome synthesis factor and an interacting partner of the nucleolar GTP-binding protein Nog1. Unlike any previously studied yeast helicases, Ddx51 is required for the formation of the 3' end of 28S rRNA. Ddx51 binds to pre-60S subunit complexes and promotes displacement of U8 snoRNA from pre-rRNA, which is necessary for the removal of the 3' external transcribed spacer from 28S rRNA and productive downstream processing. These data demonstrate the emergence of a novel factor that facilitates a pre-rRNA processing event specific for higher eukaryotes.
真核核糖体的生物发生需要许多 RNA 解旋酶，这些酶在组装途径的各个点驱动分子重排。虽然许多核糖体合成因子在所有真核生物中都保守，但核糖体成熟的某些特征，如 U8 snoRNA 辅助加工 5.8S 和 28S rRNA 前体，仅在后生动物细胞中观察到。在这里，我们鉴定出哺乳动物 DEAD 盒解旋酶家族成员 Ddx51 作为一种新的核糖体合成因子，也是核仁 GTP 结合蛋白 Nog1 的相互作用伙伴。与之前研究过的任何酵母解旋酶不同，Ddx51 是 28S rRNA 3' 端形成所必需的。Ddx51 与 pre-60S 亚基复合物结合，并促进 U8 snoRNA 从 pre-rRNA 上的位移，这对于从 28S rRNA 上除去 3' 外部转录间隔区和有效的下游加工是必要的。这些数据表明出现了一种新的因子，它促进了一种特定于高等真核生物的 pre-rRNA 加工事件。
